“Families, parents and patients across the Lothians and eastern Scotland will be deeply disappointed and frustrated at this,” said Scottish Conservative shadow health secretary Miles Briggs.

“This appears to be yet another delay to the opening of a vital new hospital facility, despite NHS Lothian guaranteeing that it would open next spring.”

Plans for new hospital were drawn up ten years ago and it was supposed to be open by the winter of 2012, only to be held up by a protracted land swap deal. Other problems included partner firms running into financial difficulties and poor winter weather hindering building work.

Mr Briggs criticised six years of delay, in which time he said Glasgow has completed a similar facility with funding from the Scottish Government.

“Families deserve answers and clarification from both NHS Lothian and the Scottish Government about the reasons behind this delay and I will be seeking these on behalf of constituents,” said Mr Briggs.

“The SNP government’s handling of this whole project – which it claims is one of its flagship infrastructure investments – has been incredibly poor from the outset, having originally indicated a new hospital could be ready by the end of

“We anticipate the Royal Hospital for Children and Young People, Department for clinical neurosciences and child & adolescents mental health services will open to patients in spring 2018.

“However, until we have the revised migration timetable agreed these dates can not be confirmed.

“This is a huge project and it’s vital that the building is fully operational before it opens to ensure we provide the best possible care to all our patients. Staff are being kept up to date with any developments on moving dates.”

A Scottish Government spokeswoman said: “NHS Lothian have made us aware of the situation and we are continuing to liaise with them to ensure everything possible is being done to ensure the new hospital opens as soon as possible.”